Doubled haploids in tropical maize: <Emphasis Type="SmallCaps">II</Emphasis>. Quantitative genetic parameters for testcross performance

Single crosses (SC) of elite inbreds and open-pollinated populations (OP) are suitable source germplasm for doubled haploid (DH) line development in hybrid maize breeding, given that they combine a high population mean ([`(x)] \overline{x} ) for testcross performance with adequate response to selection ( \Updelta G \Updelta G ). This is the first study reporting testcross grain yield (TCGY) and dry matter content (TCDMC) evaluations of 131 DH lines developed from ten tropical source germplasm comprising five OP (OP1–OP5) and five SC (SC1–SC5). Gene diversity (d) and the average number of alleles (a <sub>r</sub> ) per locus was estimated for DH lines based on 24 simple sequence repeat markers. Analysis across three environments revealed no significant differences between [`(x)] \overline{x} of OP- and SC-derived DH lines for TCGY and TCDMC. Significant genetic variance for both traits was only detected among OP-derived DH lines which may be explained by a larger number of segregating quantitative trait loci (QTL) as suggested by higher d and a _r values than in SC-derived DH lines. The usefulness criterion ( U = [`(x)] + \Updelta G U = \overline{x} + \Updelta G ) was higher for OP-derived DH lines for TCDMC, but higher for SC-derived DH lines for TCGY. DH lines from OP1, OP2, and OP3 showed high TCGY, suggesting that they may be useful in tropical hybrid breeding. We conclude that tropical OP represent a valuable source of untapped genetic variation that can efficiently be exploited with DH technology for hybrid maize breeding.     

Effect of fortifying concentrate supplement with fibrolytic enzymes on nutrient utilization, milk yield and composition in lactating goats

Thirty lactating Beetle‐sannen crossbred goats were randomly divided into 3 groups based on first fortnight milk yield, and then adjusted to body weights to study the effect of fibrolytic enzyme supplementation on digestibility and milk production. Goats in the control group (C) were fed 500 g of concentrate supplement (CS) without exogenous fibrolytic enzymes (control; CG) or CS fortified with cellulase and xylanases @ of 4000 and 12500 (EG₁) or 8000 and 18 750 IU/kg (EG₂), respectively. CS was offered in two equal proportions just after milking at 7 and 17 h. After feeding CS, goats were fed 1200 g of wheat straw as roughage in two equal parts at 08.00 and 18.00 hours. Milk yield was studied for 3½ months. Milking was done by hand. Changes in body weight were also recorded. After a preliminary period of 60 days of feeding, a 7‐day digestibility trial was conducted in two intervals with 5 animals from each group at a time. The increase in either wheat straw or NDF intake due to the enzyme mixture was only 3%. There was significant improvement (P < 0.05) in the diet digestibility of DM, OM, CP, NDF, ADF and total carbohydrates (TC) between the control and EG₁ and EG₂ goats. Improvements were greater (P < 0.05) in the latter group. Microbial protein (MBP) was estimated based on purine derivatives and creatinine excreted in spot urine samples. MBP increased about 10 and 15% in EG₁ and EG₂, but these values were statistically invalid. Phenomenally milk yield, fat and SNF were significantly (P < 0.001) changed with progression of lactation. On a temporal basis, fortnightly changes in FCM yield of this study could be grouped as 1 month each of first and last and 1½ of middle phase of lactation. Repeated measure analysis showed 180 to 260 mL/day of higher FCM and 16 to 20 g/day of higher SNF yield (P < 0.001) in EG₂ than control or even EG₁ during 5 to 7^th fortnight. However, no significant impact (P > 0.05) was noticed on TF. Feed intake, g/kg FCM yield was also 7% less in EG₂ than either CG or EG₁. The study concluded that apart from increased digestibility, fortification of CS with cellulase and xylanases enzymes improved FCM yield in the last quarter of lactation in goats, and improved body weights by 5% (P > 0.05). While the digestibility of the diet was higher in EG₁ and EG₂, the impact on FCM and SNF yield was noticed only on EG₂. Our study indicated that CS of lactating goats may be fortified with 8000 and 18 500 IU/kg CS in the last quarter of lactation.     

Axonopathy and transport deficits early in the pathogenesis of Alzheimer's disease

We identified axonal defects in mouse models of Alzheimer's disease that preceded known disease-related pathology by more than a year; we observed similar axonal defects in the early stages of Alzheimer's disease in humans. Axonal defects consisted of swellings that accumulated abnormal amounts of microtubule-associated and molecular motor proteins, organelles, and vesicles. Impairing axonal transport by reducing the dosage of a kinesin molecular motor protein enhanced the frequency of axonal defects and increased amyloid-beta peptide levels and amyloid deposition. Reductions in microtubule-dependent transport may stimulate proteolytic processing of beta-amyloid precursor protein, resulting in the development of senile plaques and Alzheimer's disease.     

Isozyme Analysis of Some Male Sterile Lines in Sorghum bicolor (L.) Moench

A comparative study of peroxidase and acid phosphatase of anthers was carried out on sorghum to characterize five male steriles and their maímainers. Differences in presence/absence and intensity of bands were observed for the isozyme patterns of all the male steriles and their corresponding maintainers. The better expression of enzymes in sterile anthers emphasized the role they play in breaking down various metabolites that are otherwise important for formation of fertile anthers.     

Chemo-biochemical Desulphurization of Various Gaseous Streams on Bench Scale

The gaseous streams containing hydrogen sulphide (H₂S) mixed with nitrogen gas (N₂) (H₂S, 0.00145 mol L^-1), H₂S mixed with liquefied petroleum gas (LPG) and refinery fuel gas were evaluated, in batch operation, in a bubbled column reactor for desulphurization using ferric sulphate as an oxidant. Further, the ferrous sulphate produced in the process of oxidation is biologically oxidized to ferric sulphate using biomass enriched with Thiobacillus ferrooxidans-JSPR1 in flask culture experiments. In all the cases, the gases were bubbled into the biologically generated ferric sulphate (from ferrous sulphate solution) for the oxidation of H₂S. The results indicate that0.00426 mol L^-1 of ferric ions are required for reacting with0.00145 mol L^-1 of H₂S in a gaseous stream containing mixture of N₂ and H₂S. A concentration of 0.00447 mol L^-1 of ferric ions is needed for oxidation of 0.00145 mol L^-1 of H₂S mixed with LPG. Similarly, the refinery fuel gas containing 0.0031 mol L^-1 of H₂S requires 0.00428 mol L^-1 of ferric ion for effective desulphurization. The ratio of moles of H₂S reacted to moles of Fe²⁺ produced at optimal condition was 0.533, 0.516, 0.510, respectively, for nitrogen mixed H₂S, LPG mixed H₂S and refinery fuel gas containing H₂S. The removal of H₂S from these gaseous streams was more than 98%sulphate produced in the process could be biologically oxidized to ferric sulphate with an efficiency of 98%, using shake flask culture experiments. Based on flask culture experiments for biooxidation of commercial ferrous sulphate to generate ferric sulphate, the biokinetic constants viz. yield coefficient y, maximum specific growth rate constant μ_max and half saturation rate constant K _s were evaluated. The yield coefficient was found to be 0.112 while μ_max and K _s were observed to be 0.1686 hr^-1 and 187.9 mg L^-1, respectively. The evaluation of biokinetic constants for bio-oxidation of ferrous sulphate generated during the scrubbing of refinery fuel gas containing H₂S indicated the value of μ_max and K _s as 0.1426 hr^-1 and 205 mg L^-1, respectively. The value of yield coefficient in this real system was found to be 0.102.     

Biotechnology initiative to achieve plant pest and disease resistance

Biotechnology applications are primarily proprietary, with 70% of the annual global research expenditures of US$11 × 10⁹ being in the private sector. The International Service for the Acquisition of Agri-Biotech Applications (ISAAA) addresses this challenge by building a new partnership of three donor groups (bilateral/multilateral agencies, private philanthropic foundations, and private companies) to support a not-for-profit institution within existing centres of excellence (Cornell University in North America, John Innes Centre in Europe, Technova in the Asian Pacific Rim, and three additional locations to be established in developing countries). Brokered projects involve only near-term technologies with a high probability of success, using tissue culture/micropropagation, disease diagnostics and transgenic plants. The main targets for transgenic plants are coat protein-mediated protection for non-conventional virus resistance (NCVR) and insecticidal proteins from Bacillus thuringiensis (Bt); both NCVR and Bt can contribute to integrated pest management strategies using reduced inputs for chemical control of insects. Four ISAAA projects demonstrate the potential of NCVR and Bt in developing countries: (1) potato resistant to potato viruses X and Y with Mexico/Monsanto/Rockefeller Foundation, (2) melon resistant to cucumber mosaic virus with Costa Rica/Asgrow Seed/USAID and the ISAAA Fellowship Program, (3) papaya resistant to papaya ringspot virus with Brazil and other countries/Cornell University/Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA), and (4) cotton resistant to Lepidoptera with Brazil/EMBRAPA. Although over 1000 field trials of transgenic plants have taken place worldwide, those experiments have been mostly small scale and do not provide sufficient data to assess either the durability of resistance achieved with genetic engineering or conclusive public acceptance of this technology. However, resistance management modelling is speculative and can not decisively indicate a deployment strategy in the absence of continued monitoring and experimentation. ISAAA's projects should allow opportunities for assessment of resistance management practices for applied plant biotechnology to control agricultural pests under diverse production systems.     

Efficacy of insecticides against major insect pests of potatoes in hot climates of Peru

Soil-incorporated and foliar-applied insecticides, alone and in combination, were tested in two different tropical sites of Peru. At San Ramon (altitude 800 m) major pests during the wet season were Diabrotica spp. and Myzus persicae. Soil-incorporated insecticides gave protection against Diabrotica but not M. persicae, and yields were significantly lower with these compared with the foliar-applied insecticide, carbofuran. Mean yield was inversely and significantly correlated with mean number of Diabrotica individuals per plant (r=0·989; 0·01 <P<0·05). The foliar-applied insecticide, season, major pests were Phthorimaea operculella, M. persicae and Feltia spp. Mean yield was inversely correlated with mean number of larval mines by P. operculella on foliage (r=0·976;0·02 <P<0·05). The foliar-applied insecticide methomyl, reduced pest damage and increased yields significantly. The major pests during the dry season at Yurimagus (altitude 180m) were Diabrotica spp. Foliar application of carbaryl alone, or in combination with soil-incorporated insecticides, was equally effective in reducing damage and yield loss. An inverse significant correlation (r=0·985; 0·01<P<0·02) for yield vs. damage from Diabrotica spp. was observed.     

Organochloride insecticide residues in air in Delhi,India

Regular monitoring of air at three different sites, namely, Netaji Nagar, Moti Nagar and Town Hall in the metropolitan city of Delhi, India from June, 1980 to May, 1982 revealed varying levels of residues of DDT and HCH. The concentration of total DDT residues varied from 4 to 232 ng m^?3 with an average of 60 ng m^?3. Total HCH ranged from 0 to 21797 ng m^?3 with an average of 438 ng m^?3. Comparatively higher levels of total DDT (73 ng M^?3) were detected at Moti Nagar, the site near a DDT factory. The total HCH was highest at Town Hall (931 ng m^?3). Normally, higher quantities of the residues of DDT and HCH were detected during October to December. The insecticide residues consisted mainly of p, p′-DDT, p, p′-DDE, o, p′-DDT and p, p′-DDD, α- and γ-HCH. Only p, p′-DDT and p, p′-DDE were detected in all the samples and accounted for the bulk of total DDT. The HCH residues were mainly due to the α-isomer. Generally the concentration of HCH was higher than DDT in the air samples collected during the survey.